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llvm-project/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp

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//===-- InstrProfiling.cpp - Frontend instrumentation based profiling -----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass lowers instrprof_* intrinsics emitted by a frontend for profiling.
// It also builds the data structures and initialization code needed for
// updating execution counts and emitting the profile at runtime.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Instrumentation/InstrProfiling.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Pass.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <string>
using namespace llvm;
#define DEBUG_TYPE "instrprof"
// The start and end values of precise value profile range for memory
// intrinsic sizes
cl::opt<std::string> MemOPSizeRange(
"memop-size-range",
cl::desc("Set the range of size in memory intrinsic calls to be profiled "
"precisely, in a format of <start_val>:<end_val>"),
cl::init(""));
// The value that considered to be large value in memory intrinsic.
cl::opt<unsigned> MemOPSizeLarge(
"memop-size-large",
cl::desc("Set large value thresthold in memory intrinsic size profiling. "
"Value of 0 disables the large value profiling."),
cl::init(8192));
namespace {
cl::opt<bool> DoNameCompression("enable-name-compression",
cl::desc("Enable name string compression"),
cl::init(true));
cl::opt<bool> DoHashBasedCounterSplit(
"hash-based-counter-split",
cl::desc("Rename counter variable of a comdat function based on cfg hash"),
cl::init(true));
cl::opt<bool> ValueProfileStaticAlloc(
"vp-static-alloc",
cl::desc("Do static counter allocation for value profiler"),
cl::init(true));
cl::opt<double> NumCountersPerValueSite(
"vp-counters-per-site",
cl::desc("The average number of profile counters allocated "
"per value profiling site."),
// This is set to a very small value because in real programs, only
// a very small percentage of value sites have non-zero targets, e.g, 1/30.
// For those sites with non-zero profile, the average number of targets
// is usually smaller than 2.
cl::init(1.0));
cl::opt<bool> AtomicCounterUpdateAll(
"instrprof-atomic-counter-update-all", cl::ZeroOrMore,
cl::desc("Make all profile counter updates atomic (for testing only)"),
cl::init(false));
cl::opt<bool> AtomicCounterUpdatePromoted(
"atomic-counter-update-promoted", cl::ZeroOrMore,
cl::desc("Do counter update using atomic fetch add "
" for promoted counters only"),
cl::init(false));
// If the option is not specified, the default behavior about whether
// counter promotion is done depends on how instrumentaiton lowering
// pipeline is setup, i.e., the default value of true of this option
// does not mean the promotion will be done by default. Explicitly
// setting this option can override the default behavior.
cl::opt<bool> DoCounterPromotion("do-counter-promotion", cl::ZeroOrMore,
cl::desc("Do counter register promotion"),
cl::init(false));
cl::opt<unsigned> MaxNumOfPromotionsPerLoop(
cl::ZeroOrMore, "max-counter-promotions-per-loop", cl::init(20),
cl::desc("Max number counter promotions per loop to avoid"
" increasing register pressure too much"));
// A debug option
cl::opt<int>
MaxNumOfPromotions(cl::ZeroOrMore, "max-counter-promotions", cl::init(-1),
cl::desc("Max number of allowed counter promotions"));
cl::opt<unsigned> SpeculativeCounterPromotionMaxExiting(
cl::ZeroOrMore, "speculative-counter-promotion-max-exiting", cl::init(3),
cl::desc("The max number of exiting blocks of a loop to allow "
" speculative counter promotion"));
cl::opt<bool> SpeculativeCounterPromotionToLoop(
cl::ZeroOrMore, "speculative-counter-promotion-to-loop", cl::init(false),
cl::desc("When the option is false, if the target block is in a loop, "
"the promotion will be disallowed unless the promoted counter "
" update can be further/iteratively promoted into an acyclic "
" region."));
cl::opt<bool> IterativeCounterPromotion(
cl::ZeroOrMore, "iterative-counter-promotion", cl::init(true),
cl::desc("Allow counter promotion across the whole loop nest."));
class InstrProfilingLegacyPass : public ModulePass {
InstrProfiling InstrProf;
public:
static char ID;
InstrProfilingLegacyPass() : ModulePass(ID) {}
InstrProfilingLegacyPass(const InstrProfOptions &Options)
: ModulePass(ID), InstrProf(Options) {}
StringRef getPassName() const override {
return "Frontend instrumentation-based coverage lowering";
}
bool runOnModule(Module &M) override {
return InstrProf.run(M, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
};
///
/// A helper class to promote one counter RMW operation in the loop
/// into register update.
///
/// RWM update for the counter will be sinked out of the loop after
/// the transformation.
///
class PGOCounterPromoterHelper : public LoadAndStorePromoter {
public:
PGOCounterPromoterHelper(
Instruction *L, Instruction *S, SSAUpdater &SSA, Value *Init,
BasicBlock *PH, ArrayRef<BasicBlock *> ExitBlocks,
ArrayRef<Instruction *> InsertPts,
DenseMap<Loop *, SmallVector<LoadStorePair, 8>> &LoopToCands,
LoopInfo &LI)
: LoadAndStorePromoter({L, S}, SSA), Store(S), ExitBlocks(ExitBlocks),
InsertPts(InsertPts), LoopToCandidates(LoopToCands), LI(LI) {
assert(isa<LoadInst>(L));
assert(isa<StoreInst>(S));
SSA.AddAvailableValue(PH, Init);
}
void doExtraRewritesBeforeFinalDeletion() const override {
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
BasicBlock *ExitBlock = ExitBlocks[i];
Instruction *InsertPos = InsertPts[i];
// Get LiveIn value into the ExitBlock. If there are multiple
// predecessors, the value is defined by a PHI node in this
// block.
Value *LiveInValue = SSA.GetValueInMiddleOfBlock(ExitBlock);
Value *Addr = cast<StoreInst>(Store)->getPointerOperand();
IRBuilder<> Builder(InsertPos);
if (AtomicCounterUpdatePromoted)
// automic update currently can only be promoted across the current
// loop, not the whole loop nest.
Builder.CreateAtomicRMW(AtomicRMWInst::Add, Addr, LiveInValue,
AtomicOrdering::SequentiallyConsistent);
else {
LoadInst *OldVal = Builder.CreateLoad(Addr, "pgocount.promoted");
auto *NewVal = Builder.CreateAdd(OldVal, LiveInValue);
auto *NewStore = Builder.CreateStore(NewVal, Addr);
// Now update the parent loop's candidate list:
if (IterativeCounterPromotion) {
auto *TargetLoop = LI.getLoopFor(ExitBlock);
if (TargetLoop)
LoopToCandidates[TargetLoop].emplace_back(OldVal, NewStore);
}
}
}
}
private:
Instruction *Store;
ArrayRef<BasicBlock *> ExitBlocks;
ArrayRef<Instruction *> InsertPts;
DenseMap<Loop *, SmallVector<LoadStorePair, 8>> &LoopToCandidates;
LoopInfo &LI;
};
/// A helper class to do register promotion for all profile counter
/// updates in a loop.
///
class PGOCounterPromoter {
public:
PGOCounterPromoter(
DenseMap<Loop *, SmallVector<LoadStorePair, 8>> &LoopToCands,
Loop &CurLoop, LoopInfo &LI)
: LoopToCandidates(LoopToCands), ExitBlocks(), InsertPts(), L(CurLoop),
LI(LI) {
SmallVector<BasicBlock *, 8> LoopExitBlocks;
SmallPtrSet<BasicBlock *, 8> BlockSet;
L.getExitBlocks(LoopExitBlocks);
for (BasicBlock *ExitBlock : LoopExitBlocks) {
if (BlockSet.insert(ExitBlock).second) {
ExitBlocks.push_back(ExitBlock);
InsertPts.push_back(&*ExitBlock->getFirstInsertionPt());
}
}
}
bool run(int64_t *NumPromoted) {
// Skip 'infinite' loops:
if (ExitBlocks.size() == 0)
return false;
unsigned MaxProm = getMaxNumOfPromotionsInLoop(&L);
if (MaxProm == 0)
return false;
unsigned Promoted = 0;
for (auto &Cand : LoopToCandidates[&L]) {
SmallVector<PHINode *, 4> NewPHIs;
SSAUpdater SSA(&NewPHIs);
Value *InitVal = ConstantInt::get(Cand.first->getType(), 0);
PGOCounterPromoterHelper Promoter(Cand.first, Cand.second, SSA, InitVal,
L.getLoopPreheader(), ExitBlocks,
InsertPts, LoopToCandidates, LI);
Promoter.run(SmallVector<Instruction *, 2>({Cand.first, Cand.second}));
Promoted++;
if (Promoted >= MaxProm)
break;
(*NumPromoted)++;
if (MaxNumOfPromotions != -1 && *NumPromoted >= MaxNumOfPromotions)
break;
}
LLVM_DEBUG(dbgs() << Promoted << " counters promoted for loop (depth="
<< L.getLoopDepth() << ")\n");
return Promoted != 0;
}
private:
bool allowSpeculativeCounterPromotion(Loop *LP) {
SmallVector<BasicBlock *, 8> ExitingBlocks;
L.getExitingBlocks(ExitingBlocks);
// Not considierered speculative.
if (ExitingBlocks.size() == 1)
return true;
if (ExitingBlocks.size() > SpeculativeCounterPromotionMaxExiting)
return false;
return true;
}
// Returns the max number of Counter Promotions for LP.
unsigned getMaxNumOfPromotionsInLoop(Loop *LP) {
// We can't insert into a catchswitch.
SmallVector<BasicBlock *, 8> LoopExitBlocks;
LP->getExitBlocks(LoopExitBlocks);
if (llvm::any_of(LoopExitBlocks, [](BasicBlock *Exit) {
return isa<CatchSwitchInst>(Exit->getTerminator());
}))
return 0;
if (!LP->hasDedicatedExits())
return 0;
BasicBlock *PH = LP->getLoopPreheader();
if (!PH)
return 0;
SmallVector<BasicBlock *, 8> ExitingBlocks;
LP->getExitingBlocks(ExitingBlocks);
// Not considierered speculative.
if (ExitingBlocks.size() == 1)
return MaxNumOfPromotionsPerLoop;
if (ExitingBlocks.size() > SpeculativeCounterPromotionMaxExiting)
return 0;
// Whether the target block is in a loop does not matter:
if (SpeculativeCounterPromotionToLoop)
return MaxNumOfPromotionsPerLoop;
// Now check the target block:
unsigned MaxProm = MaxNumOfPromotionsPerLoop;
for (auto *TargetBlock : LoopExitBlocks) {
auto *TargetLoop = LI.getLoopFor(TargetBlock);
if (!TargetLoop)
continue;
unsigned MaxPromForTarget = getMaxNumOfPromotionsInLoop(TargetLoop);
unsigned PendingCandsInTarget = LoopToCandidates[TargetLoop].size();
MaxProm =
std::min(MaxProm, std::max(MaxPromForTarget, PendingCandsInTarget) -
PendingCandsInTarget);
}
return MaxProm;
}
DenseMap<Loop *, SmallVector<LoadStorePair, 8>> &LoopToCandidates;
SmallVector<BasicBlock *, 8> ExitBlocks;
SmallVector<Instruction *, 8> InsertPts;
Loop &L;
LoopInfo &LI;
};
} // end anonymous namespace
PreservedAnalyses InstrProfiling::run(Module &M, ModuleAnalysisManager &AM) {
auto &TLI = AM.getResult<TargetLibraryAnalysis>(M);
if (!run(M, TLI))
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}
char InstrProfilingLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(
InstrProfilingLegacyPass, "instrprof",
"Frontend instrumentation-based coverage lowering.", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(
InstrProfilingLegacyPass, "instrprof",
"Frontend instrumentation-based coverage lowering.", false, false)
ModulePass *
llvm::createInstrProfilingLegacyPass(const InstrProfOptions &Options) {
return new InstrProfilingLegacyPass(Options);
}
static InstrProfIncrementInst *castToIncrementInst(Instruction *Instr) {
InstrProfIncrementInst *Inc = dyn_cast<InstrProfIncrementInstStep>(Instr);
if (Inc)
return Inc;
return dyn_cast<InstrProfIncrementInst>(Instr);
}
bool InstrProfiling::lowerIntrinsics(Function *F) {
bool MadeChange = false;
PromotionCandidates.clear();
for (BasicBlock &BB : *F) {
for (auto I = BB.begin(), E = BB.end(); I != E;) {
auto Instr = I++;
InstrProfIncrementInst *Inc = castToIncrementInst(&*Instr);
if (Inc) {
lowerIncrement(Inc);
MadeChange = true;
} else if (auto *Ind = dyn_cast<InstrProfValueProfileInst>(Instr)) {
lowerValueProfileInst(Ind);
MadeChange = true;
}
}
}
if (!MadeChange)
return false;
promoteCounterLoadStores(F);
return true;
}
bool InstrProfiling::isCounterPromotionEnabled() const {
if (DoCounterPromotion.getNumOccurrences() > 0)
return DoCounterPromotion;
return Options.DoCounterPromotion;
}
void InstrProfiling::promoteCounterLoadStores(Function *F) {
if (!isCounterPromotionEnabled())
return;
DominatorTree DT(*F);
LoopInfo LI(DT);
DenseMap<Loop *, SmallVector<LoadStorePair, 8>> LoopPromotionCandidates;
for (const auto &LoadStore : PromotionCandidates) {
auto *CounterLoad = LoadStore.first;
auto *CounterStore = LoadStore.second;
BasicBlock *BB = CounterLoad->getParent();
Loop *ParentLoop = LI.getLoopFor(BB);
if (!ParentLoop)
continue;
LoopPromotionCandidates[ParentLoop].emplace_back(CounterLoad, CounterStore);
}
SmallVector<Loop *, 4> Loops = LI.getLoopsInPreorder();
// Do a post-order traversal of the loops so that counter updates can be
// iteratively hoisted outside the loop nest.
for (auto *Loop : llvm::reverse(Loops)) {
PGOCounterPromoter Promoter(LoopPromotionCandidates, *Loop, LI);
Promoter.run(&TotalCountersPromoted);
}
}
/// Check if the module contains uses of any profiling intrinsics.
static bool containsProfilingIntrinsics(Module &M) {
if (auto *F = M.getFunction(
Intrinsic::getName(llvm::Intrinsic::instrprof_increment)))
if (!F->use_empty())
return true;
if (auto *F = M.getFunction(
Intrinsic::getName(llvm::Intrinsic::instrprof_increment_step)))
if (!F->use_empty())
return true;
if (auto *F = M.getFunction(
Intrinsic::getName(llvm::Intrinsic::instrprof_value_profile)))
if (!F->use_empty())
return true;
return false;
}
bool InstrProfiling::run(Module &M, const TargetLibraryInfo &TLI) {
this->M = &M;
this->TLI = &TLI;
NamesVar = nullptr;
NamesSize = 0;
ProfileDataMap.clear();
UsedVars.clear();
getMemOPSizeRangeFromOption(MemOPSizeRange, MemOPSizeRangeStart,
MemOPSizeRangeLast);
TT = Triple(M.getTargetTriple());
// Emit the runtime hook even if no counters are present.
bool MadeChange = emitRuntimeHook();
// Improve compile time by avoiding linear scans when there is no work.
GlobalVariable *CoverageNamesVar =
M.getNamedGlobal(getCoverageUnusedNamesVarName());
if (!containsProfilingIntrinsics(M) && !CoverageNamesVar)
return MadeChange;
// We did not know how many value sites there would be inside
// the instrumented function. This is counting the number of instrumented
// target value sites to enter it as field in the profile data variable.
for (Function &F : M) {
InstrProfIncrementInst *FirstProfIncInst = nullptr;
for (BasicBlock &BB : F)
for (auto I = BB.begin(), E = BB.end(); I != E; I++)
if (auto *Ind = dyn_cast<InstrProfValueProfileInst>(I))
computeNumValueSiteCounts(Ind);
else if (FirstProfIncInst == nullptr)
FirstProfIncInst = dyn_cast<InstrProfIncrementInst>(I);
// Value profiling intrinsic lowering requires per-function profile data
// variable to be created first.
if (FirstProfIncInst != nullptr)
static_cast<void>(getOrCreateRegionCounters(FirstProfIncInst));
}
for (Function &F : M)
MadeChange |= lowerIntrinsics(&F);
if (CoverageNamesVar) {
lowerCoverageData(CoverageNamesVar);
MadeChange = true;
}
if (!MadeChange)
return false;
emitVNodes();
emitNameData();
emitRegistration();
emitUses();
emitInitialization();
return true;
}
static Constant *getOrInsertValueProfilingCall(Module &M,
const TargetLibraryInfo &TLI,
bool IsRange = false) {
LLVMContext &Ctx = M.getContext();
auto *ReturnTy = Type::getVoidTy(M.getContext());
Constant *Res;
if (!IsRange) {
Type *ParamTypes[] = {
#define VALUE_PROF_FUNC_PARAM(ParamType, ParamName, ParamLLVMType) ParamLLVMType
#include "llvm/ProfileData/InstrProfData.inc"
};
auto *ValueProfilingCallTy =
FunctionType::get(ReturnTy, makeArrayRef(ParamTypes), false);
Res = M.getOrInsertFunction(getInstrProfValueProfFuncName(),
ValueProfilingCallTy);
} else {
Type *RangeParamTypes[] = {
#define VALUE_RANGE_PROF 1
#define VALUE_PROF_FUNC_PARAM(ParamType, ParamName, ParamLLVMType) ParamLLVMType
#include "llvm/ProfileData/InstrProfData.inc"
#undef VALUE_RANGE_PROF
};
auto *ValueRangeProfilingCallTy =
FunctionType::get(ReturnTy, makeArrayRef(RangeParamTypes), false);
Res = M.getOrInsertFunction(getInstrProfValueRangeProfFuncName(),
ValueRangeProfilingCallTy);
}
if (Function *FunRes = dyn_cast<Function>(Res)) {
if (auto AK = TLI.getExtAttrForI32Param(false))
FunRes->addParamAttr(2, AK);
}
return Res;
}
void InstrProfiling::computeNumValueSiteCounts(InstrProfValueProfileInst *Ind) {
GlobalVariable *Name = Ind->getName();
uint64_t ValueKind = Ind->getValueKind()->getZExtValue();
uint64_t Index = Ind->getIndex()->getZExtValue();
auto It = ProfileDataMap.find(Name);
if (It == ProfileDataMap.end()) {
PerFunctionProfileData PD;
PD.NumValueSites[ValueKind] = Index + 1;
ProfileDataMap[Name] = PD;
} else if (It->second.NumValueSites[ValueKind] <= Index)
It->second.NumValueSites[ValueKind] = Index + 1;
}
void InstrProfiling::lowerValueProfileInst(InstrProfValueProfileInst *Ind) {
GlobalVariable *Name = Ind->getName();
auto It = ProfileDataMap.find(Name);
assert(It != ProfileDataMap.end() && It->second.DataVar &&
"value profiling detected in function with no counter incerement");
GlobalVariable *DataVar = It->second.DataVar;
uint64_t ValueKind = Ind->getValueKind()->getZExtValue();
uint64_t Index = Ind->getIndex()->getZExtValue();
for (uint32_t Kind = IPVK_First; Kind < ValueKind; ++Kind)
Index += It->second.NumValueSites[Kind];
IRBuilder<> Builder(Ind);
bool IsRange = (Ind->getValueKind()->getZExtValue() ==
llvm::InstrProfValueKind::IPVK_MemOPSize);
CallInst *Call = nullptr;
if (!IsRange) {
Value *Args[3] = {Ind->getTargetValue(),
Builder.CreateBitCast(DataVar, Builder.getInt8PtrTy()),
Builder.getInt32(Index)};
Call = Builder.CreateCall(getOrInsertValueProfilingCall(*M, *TLI), Args);
} else {
Value *Args[6] = {
Ind->getTargetValue(),
Builder.CreateBitCast(DataVar, Builder.getInt8PtrTy()),
Builder.getInt32(Index),
Builder.getInt64(MemOPSizeRangeStart),
Builder.getInt64(MemOPSizeRangeLast),
Builder.getInt64(MemOPSizeLarge == 0 ? INT64_MIN : MemOPSizeLarge)};
Call =
Builder.CreateCall(getOrInsertValueProfilingCall(*M, *TLI, true), Args);
}
if (auto AK = TLI->getExtAttrForI32Param(false))
Call->addParamAttr(2, AK);
Ind->replaceAllUsesWith(Call);
Ind->eraseFromParent();
}
void InstrProfiling::lowerIncrement(InstrProfIncrementInst *Inc) {
GlobalVariable *Counters = getOrCreateRegionCounters(Inc);
IRBuilder<> Builder(Inc);
uint64_t Index = Inc->getIndex()->getZExtValue();
Value *Addr = Builder.CreateConstInBoundsGEP2_64(Counters, 0, Index);
if (Options.Atomic || AtomicCounterUpdateAll) {
Builder.CreateAtomicRMW(AtomicRMWInst::Add, Addr, Inc->getStep(),
AtomicOrdering::Monotonic);
} else {
Value *Load = Builder.CreateLoad(Addr, "pgocount");
auto *Count = Builder.CreateAdd(Load, Inc->getStep());
auto *Store = Builder.CreateStore(Count, Addr);
if (isCounterPromotionEnabled())
PromotionCandidates.emplace_back(cast<Instruction>(Load), Store);
}
Inc->eraseFromParent();
}
void InstrProfiling::lowerCoverageData(GlobalVariable *CoverageNamesVar) {
ConstantArray *Names =
cast<ConstantArray>(CoverageNamesVar->getInitializer());
for (unsigned I = 0, E = Names->getNumOperands(); I < E; ++I) {
Constant *NC = Names->getOperand(I);
Value *V = NC->stripPointerCasts();
assert(isa<GlobalVariable>(V) && "Missing reference to function name");
GlobalVariable *Name = cast<GlobalVariable>(V);
Name->setLinkage(GlobalValue::PrivateLinkage);
ReferencedNames.push_back(Name);
NC->dropAllReferences();
}
CoverageNamesVar->eraseFromParent();
}
/// Get the name of a profiling variable for a particular function.
static std::string getVarName(InstrProfIncrementInst *Inc, StringRef Prefix) {
StringRef NamePrefix = getInstrProfNameVarPrefix();
StringRef Name = Inc->getName()->getName().substr(NamePrefix.size());
Function *F = Inc->getParent()->getParent();
Module *M = F->getParent();
if (!DoHashBasedCounterSplit || !isIRPGOFlagSet(M) ||
!canRenameComdatFunc(*F))
return (Prefix + Name).str();
uint64_t FuncHash = Inc->getHash()->getZExtValue();
SmallVector<char, 24> HashPostfix;
if (Name.endswith((Twine(".") + Twine(FuncHash)).toStringRef(HashPostfix)))
return (Prefix + Name).str();
return (Prefix + Name + "." + Twine(FuncHash)).str();
}
static inline bool shouldRecordFunctionAddr(Function *F) {
// Check the linkage
bool HasAvailableExternallyLinkage = F->hasAvailableExternallyLinkage();
if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() &&
!HasAvailableExternallyLinkage)
return true;
// A function marked 'alwaysinline' with available_externally linkage can't
// have its address taken. Doing so would create an undefined external ref to
// the function, which would fail to link.
if (HasAvailableExternallyLinkage &&
F->hasFnAttribute(Attribute::AlwaysInline))
return false;
// Prohibit function address recording if the function is both internal and
// COMDAT. This avoids the profile data variable referencing internal symbols
// in COMDAT.
if (F->hasLocalLinkage() && F->hasComdat())
return false;
// Check uses of this function for other than direct calls or invokes to it.
// Inline virtual functions have linkeOnceODR linkage. When a key method
// exists, the vtable will only be emitted in the TU where the key method
// is defined. In a TU where vtable is not available, the function won't
// be 'addresstaken'. If its address is not recorded here, the profile data
// with missing address may be picked by the linker leading to missing
// indirect call target info.
return F->hasAddressTaken() || F->hasLinkOnceLinkage();
}
static inline Comdat *getOrCreateProfileComdat(Module &M, Function &F,
InstrProfIncrementInst *Inc) {
if (!needsComdatForCounter(F, M))
return nullptr;
// COFF format requires a COMDAT section to have a key symbol with the same
// name. The linker targeting COFF also requires that the COMDAT
// a section is associated to must precede the associating section. For this
// reason, we must choose the counter var's name as the name of the comdat.
StringRef ComdatPrefix = (Triple(M.getTargetTriple()).isOSBinFormatCOFF()
? getInstrProfCountersVarPrefix()
: getInstrProfComdatPrefix());
return M.getOrInsertComdat(StringRef(getVarName(Inc, ComdatPrefix)));
}
static bool needsRuntimeRegistrationOfSectionRange(const Module &M) {
// Don't do this for Darwin. compiler-rt uses linker magic.
if (Triple(M.getTargetTriple()).isOSDarwin())
return false;
// Use linker script magic to get data/cnts/name start/end.
if (Triple(M.getTargetTriple()).isOSLinux() ||
Triple(M.getTargetTriple()).isOSFreeBSD() ||
Triple(M.getTargetTriple()).isOSNetBSD() ||
Triple(M.getTargetTriple()).isOSFuchsia() ||
Triple(M.getTargetTriple()).isPS4CPU())
return false;
return true;
}
GlobalVariable *
InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
GlobalVariable *NamePtr = Inc->getName();
auto It = ProfileDataMap.find(NamePtr);
PerFunctionProfileData PD;
if (It != ProfileDataMap.end()) {
if (It->second.RegionCounters)
return It->second.RegionCounters;
PD = It->second;
}
// Move the name variable to the right section. Place them in a COMDAT group
// if the associated function is a COMDAT. This will make sure that
// only one copy of counters of the COMDAT function will be emitted after
// linking.
Function *Fn = Inc->getParent()->getParent();
Comdat *ProfileVarsComdat = nullptr;
ProfileVarsComdat = getOrCreateProfileComdat(*M, *Fn, Inc);
uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
LLVMContext &Ctx = M->getContext();
ArrayType *CounterTy = ArrayType::get(Type::getInt64Ty(Ctx), NumCounters);
// Create the counters variable.
auto *CounterPtr =
new GlobalVariable(*M, CounterTy, false, NamePtr->getLinkage(),
Constant::getNullValue(CounterTy),
getVarName(Inc, getInstrProfCountersVarPrefix()));
CounterPtr->setVisibility(NamePtr->getVisibility());
CounterPtr->setSection(
getInstrProfSectionName(IPSK_cnts, TT.getObjectFormat()));
CounterPtr->setAlignment(8);
CounterPtr->setComdat(ProfileVarsComdat);
auto *Int8PtrTy = Type::getInt8PtrTy(Ctx);
// Allocate statically the array of pointers to value profile nodes for
// the current function.
Constant *ValuesPtrExpr = ConstantPointerNull::get(Int8PtrTy);
if (ValueProfileStaticAlloc && !needsRuntimeRegistrationOfSectionRange(*M)) {
uint64_t NS = 0;
for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
NS += PD.NumValueSites[Kind];
if (NS) {
ArrayType *ValuesTy = ArrayType::get(Type::getInt64Ty(Ctx), NS);
auto *ValuesVar =
new GlobalVariable(*M, ValuesTy, false, NamePtr->getLinkage(),
Constant::getNullValue(ValuesTy),
getVarName(Inc, getInstrProfValuesVarPrefix()));
ValuesVar->setVisibility(NamePtr->getVisibility());
ValuesVar->setSection(
getInstrProfSectionName(IPSK_vals, TT.getObjectFormat()));
ValuesVar->setAlignment(8);
ValuesVar->setComdat(ProfileVarsComdat);
ValuesPtrExpr =
ConstantExpr::getBitCast(ValuesVar, Type::getInt8PtrTy(Ctx));
}
}
// Create data variable.
auto *Int16Ty = Type::getInt16Ty(Ctx);
auto *Int16ArrayTy = ArrayType::get(Int16Ty, IPVK_Last + 1);
Type *DataTypes[] = {
#define INSTR_PROF_DATA(Type, LLVMType, Name, Init) LLVMType,
#include "llvm/ProfileData/InstrProfData.inc"
};
auto *DataTy = StructType::get(Ctx, makeArrayRef(DataTypes));
Constant *FunctionAddr = shouldRecordFunctionAddr(Fn)
? ConstantExpr::getBitCast(Fn, Int8PtrTy)
: ConstantPointerNull::get(Int8PtrTy);
Constant *Int16ArrayVals[IPVK_Last + 1];
for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
Int16ArrayVals[Kind] = ConstantInt::get(Int16Ty, PD.NumValueSites[Kind]);
Constant *DataVals[] = {
#define INSTR_PROF_DATA(Type, LLVMType, Name, Init) Init,
#include "llvm/ProfileData/InstrProfData.inc"
};
auto *Data = new GlobalVariable(*M, DataTy, false, NamePtr->getLinkage(),
ConstantStruct::get(DataTy, DataVals),
getVarName(Inc, getInstrProfDataVarPrefix()));
Data->setVisibility(NamePtr->getVisibility());
Data->setSection(getInstrProfSectionName(IPSK_data, TT.getObjectFormat()));
Data->setAlignment(INSTR_PROF_DATA_ALIGNMENT);
Data->setComdat(ProfileVarsComdat);
PD.RegionCounters = CounterPtr;
PD.DataVar = Data;
ProfileDataMap[NamePtr] = PD;
// Mark the data variable as used so that it isn't stripped out.
UsedVars.push_back(Data);
// Now that the linkage set by the FE has been passed to the data and counter
// variables, reset Name variable's linkage and visibility to private so that
// it can be removed later by the compiler.
NamePtr->setLinkage(GlobalValue::PrivateLinkage);
// Collect the referenced names to be used by emitNameData.
ReferencedNames.push_back(NamePtr);
return CounterPtr;
}
void InstrProfiling::emitVNodes() {
if (!ValueProfileStaticAlloc)
return;
// For now only support this on platforms that do
// not require runtime registration to discover
// named section start/end.
if (needsRuntimeRegistrationOfSectionRange(*M))
return;
size_t TotalNS = 0;
for (auto &PD : ProfileDataMap) {
for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
TotalNS += PD.second.NumValueSites[Kind];
}
if (!TotalNS)
return;
uint64_t NumCounters = TotalNS * NumCountersPerValueSite;
// Heuristic for small programs with very few total value sites.
// The default value of vp-counters-per-site is chosen based on
// the observation that large apps usually have a low percentage
// of value sites that actually have any profile data, and thus
// the average number of counters per site is low. For small
// apps with very few sites, this may not be true. Bump up the
// number of counters in this case.
#define INSTR_PROF_MIN_VAL_COUNTS 10
if (NumCounters < INSTR_PROF_MIN_VAL_COUNTS)
NumCounters = std::max(INSTR_PROF_MIN_VAL_COUNTS, (int)NumCounters * 2);
auto &Ctx = M->getContext();
Type *VNodeTypes[] = {
#define INSTR_PROF_VALUE_NODE(Type, LLVMType, Name, Init) LLVMType,
#include "llvm/ProfileData/InstrProfData.inc"
};
auto *VNodeTy = StructType::get(Ctx, makeArrayRef(VNodeTypes));
ArrayType *VNodesTy = ArrayType::get(VNodeTy, NumCounters);
auto *VNodesVar = new GlobalVariable(
*M, VNodesTy, false, GlobalValue::PrivateLinkage,
Constant::getNullValue(VNodesTy), getInstrProfVNodesVarName());
VNodesVar->setSection(
getInstrProfSectionName(IPSK_vnodes, TT.getObjectFormat()));
UsedVars.push_back(VNodesVar);
}
void InstrProfiling::emitNameData() {
std::string UncompressedData;
if (ReferencedNames.empty())
return;
std::string CompressedNameStr;
if (Error E = collectPGOFuncNameStrings(ReferencedNames, CompressedNameStr,
DoNameCompression)) {
report_fatal_error(toString(std::move(E)), false);
}
auto &Ctx = M->getContext();
auto *NamesVal = ConstantDataArray::getString(
Ctx, StringRef(CompressedNameStr), false);
NamesVar = new GlobalVariable(*M, NamesVal->getType(), true,
GlobalValue::PrivateLinkage, NamesVal,
getInstrProfNamesVarName());
NamesSize = CompressedNameStr.size();
NamesVar->setSection(
getInstrProfSectionName(IPSK_name, TT.getObjectFormat()));
UsedVars.push_back(NamesVar);
for (auto *NamePtr : ReferencedNames)
NamePtr->eraseFromParent();
}
void InstrProfiling::emitRegistration() {
if (!needsRuntimeRegistrationOfSectionRange(*M))
return;
// Construct the function.
auto *VoidTy = Type::getVoidTy(M->getContext());
auto *VoidPtrTy = Type::getInt8PtrTy(M->getContext());
auto *Int64Ty = Type::getInt64Ty(M->getContext());
auto *RegisterFTy = FunctionType::get(VoidTy, false);
auto *RegisterF = Function::Create(RegisterFTy, GlobalValue::InternalLinkage,
getInstrProfRegFuncsName(), M);
RegisterF->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
if (Options.NoRedZone)
RegisterF->addFnAttr(Attribute::NoRedZone);
auto *RuntimeRegisterTy = FunctionType::get(VoidTy, VoidPtrTy, false);
auto *RuntimeRegisterF =
Function::Create(RuntimeRegisterTy, GlobalVariable::ExternalLinkage,
getInstrProfRegFuncName(), M);
IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", RegisterF));
for (Value *Data : UsedVars)
if (Data != NamesVar && !isa<Function>(Data))
IRB.CreateCall(RuntimeRegisterF, IRB.CreateBitCast(Data, VoidPtrTy));
if (NamesVar) {
Type *ParamTypes[] = {VoidPtrTy, Int64Ty};
auto *NamesRegisterTy =
FunctionType::get(VoidTy, makeArrayRef(ParamTypes), false);
auto *NamesRegisterF =
Function::Create(NamesRegisterTy, GlobalVariable::ExternalLinkage,
getInstrProfNamesRegFuncName(), M);
IRB.CreateCall(NamesRegisterF, {IRB.CreateBitCast(NamesVar, VoidPtrTy),
IRB.getInt64(NamesSize)});
}
IRB.CreateRetVoid();
}
bool InstrProfiling::emitRuntimeHook() {
// We expect the linker to be invoked with -u<hook_var> flag for linux,
// for which case there is no need to emit the user function.
if (Triple(M->getTargetTriple()).isOSLinux())
return false;
// If the module's provided its own runtime, we don't need to do anything.
if (M->getGlobalVariable(getInstrProfRuntimeHookVarName()))
return false;
// Declare an external variable that will pull in the runtime initialization.
auto *Int32Ty = Type::getInt32Ty(M->getContext());
auto *Var =
new GlobalVariable(*M, Int32Ty, false, GlobalValue::ExternalLinkage,
nullptr, getInstrProfRuntimeHookVarName());
// Make a function that uses it.
auto *User = Function::Create(FunctionType::get(Int32Ty, false),
GlobalValue::LinkOnceODRLinkage,
getInstrProfRuntimeHookVarUseFuncName(), M);
User->addFnAttr(Attribute::NoInline);
if (Options.NoRedZone)
User->addFnAttr(Attribute::NoRedZone);
User->setVisibility(GlobalValue::HiddenVisibility);
if (Triple(M->getTargetTriple()).supportsCOMDAT())
User->setComdat(M->getOrInsertComdat(User->getName()));
IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", User));
auto *Load = IRB.CreateLoad(Var);
IRB.CreateRet(Load);
// Mark the user variable as used so that it isn't stripped out.
UsedVars.push_back(User);
return true;
}
void InstrProfiling::emitUses() {
if (!UsedVars.empty())
appendToUsed(*M, UsedVars);
}
void InstrProfiling::emitInitialization() {
StringRef InstrProfileOutput = Options.InstrProfileOutput;
if (!InstrProfileOutput.empty()) {
// Create variable for profile name.
Constant *ProfileNameConst =
ConstantDataArray::getString(M->getContext(), InstrProfileOutput, true);
GlobalVariable *ProfileNameVar = new GlobalVariable(
*M, ProfileNameConst->getType(), true, GlobalValue::WeakAnyLinkage,
ProfileNameConst, INSTR_PROF_QUOTE(INSTR_PROF_PROFILE_NAME_VAR));
if (TT.supportsCOMDAT()) {
ProfileNameVar->setLinkage(GlobalValue::ExternalLinkage);
ProfileNameVar->setComdat(M->getOrInsertComdat(
StringRef(INSTR_PROF_QUOTE(INSTR_PROF_PROFILE_NAME_VAR))));
}
}
Constant *RegisterF = M->getFunction(getInstrProfRegFuncsName());
if (!RegisterF)
return;
// Create the initialization function.
auto *VoidTy = Type::getVoidTy(M->getContext());
auto *F = Function::Create(FunctionType::get(VoidTy, false),
GlobalValue::InternalLinkage,
getInstrProfInitFuncName(), M);
F->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
F->addFnAttr(Attribute::NoInline);
if (Options.NoRedZone)
F->addFnAttr(Attribute::NoRedZone);
// Add the basic block and the necessary calls.
IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", F));
if (RegisterF)
IRB.CreateCall(RegisterF, {});
IRB.CreateRetVoid();
appendToGlobalCtors(*M, F, 0);
}
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